The invention is based on an apparatus for governing the idling rpm of an internal combustion engine of an internal combustion engine. Such an apparatus has been set forth in U.S. Pat. No. 4,724,349, in which a hollow shaft having a rotary armature and a rotary slide valve that controls the bypass line is supported on a stationary shaft that is retained in a connecting body disposed on one end in a lid-like housing part and on the other in a cup-shaped housing part. Because of the large tolerances required, this kind of support of the rotary slide valve necessitates relatively large play between the circumference of the rotary slide valve and the wall of the pivoting space into which the rotary slide valve protrudes; otherwise, the rotary slide valve, if it is not supported 100% coaxially with the pivoting space, might scrape the wall of the pivoting space. Because of the pressure drop that prevails between atmospheric pressure and the negative pressure prevailing when the engine is running, air incorrectly flows via this undesirably large play between the circumference of the rotary slide valve and the wall of the pivoting space and undesirably impairs the governing process.